Article date: March 1998
By: Christian Pinna, Gillian E. Knight, Lina Puglisi, Geoffrey Burnstock, in Volume 123, Issue 6, pages 1281-1287
Purinergic and cholinergic components of parasympathetic neurotransmission and contractile responses to exogenous α,β‐methylene ATP, acetylcholine, substance K, substance P, calcitonin gene‐related peptide, vasoactive intestinal polypeptide and capsaicin have been investigated in the urinary bladder of hibernating hamsters (4 weeks), cold exposed (4 weeks) and age‐matched controls.
Electrical field stimulation (EFS) evoked increased frequency‐dependent contractions in the detrusor strips from hibernating hamsters compared with those obtained from cold‐exposed and age‐matched animals. Tetrodotoxin (10−6 M) completely blocked the frequency‐dependent contractions in all groups.
The purinergic component of the parasympathetic neurotransmission was not affected in hibernating and cold‐exposed animals while the cholinergic component was increased with respect to age‐matched animals. The neurogenic response to EFS, still present after incubation with atropine (10−6 M) and suramin (10−4 M), was attenuated by indomethacin (10−6 M) and blocked by tetrodotoxin (10−6 M).
Exogenous administration of α,β‐methylene ATP elicited a significantly reduced contraction in strips from hibernating and cold‐exposed hamsters relative to age‐matched animals. The contractile response to exogenous acetylcholine was greater in the detrusors from hibernating hamsters than in cold‐exposed and age‐matched animals. Substance K elicited reduced contractions in preparations from hibernating animals compared with cold‐exposed and control animals. Calcitonin gene‐related peptide, vasoactive intestinal polypeptide, substance P and capsaicin did not elicit any relaxant or contractile response either at resting tone or in carbachol (5×10−7 M)‐precontracted tissues.
In summary, our findings indicate that 4 weeks of hibernation can significantly increase neurogenic responses in the hamster urinary bladder. This appears to be due to an increase in postjunctional responses to acetylcholine. In contrast, there was a decrease of the postjunctional responses to the parasympathetic cotransmitter ATP and also to the sensory‐motor neurotransmitter substance K.
Purinergic and cholinergic components of parasympathetic neurotransmission and contractile responses to exogenous α,β‐methylene ATP, acetylcholine, substance K, substance P, calcitonin gene‐related peptide, vasoactive intestinal polypeptide and capsaicin have been investigated in the urinary bladder of hibernating hamsters (4 weeks), cold exposed (4 weeks) and age‐matched controls.
Electrical field stimulation (EFS) evoked increased frequency‐dependent contractions in the detrusor strips from hibernating hamsters compared with those obtained from cold‐exposed and age‐matched animals. Tetrodotoxin (10−6 M) completely blocked the frequency‐dependent contractions in all groups.
The purinergic component of the parasympathetic neurotransmission was not affected in hibernating and cold‐exposed animals while the cholinergic component was increased with respect to age‐matched animals. The neurogenic response to EFS, still present after incubation with atropine (10−6 M) and suramin (10−4 M), was attenuated by indomethacin (10−6 M) and blocked by tetrodotoxin (10−6 M).
Exogenous administration of α,β‐methylene ATP elicited a significantly reduced contraction in strips from hibernating and cold‐exposed hamsters relative to age‐matched animals. The contractile response to exogenous acetylcholine was greater in the detrusors from hibernating hamsters than in cold‐exposed and age‐matched animals. Substance K elicited reduced contractions in preparations from hibernating animals compared with cold‐exposed and control animals. Calcitonin gene‐related peptide, vasoactive intestinal polypeptide, substance P and capsaicin did not elicit any relaxant or contractile response either at resting tone or in carbachol (5×10−7 M)‐precontracted tissues.
In summary, our findings indicate that 4 weeks of hibernation can significantly increase neurogenic responses in the hamster urinary bladder. This appears to be due to an increase in postjunctional responses to acetylcholine. In contrast, there was a decrease of the postjunctional responses to the parasympathetic cotransmitter ATP and also to the sensory‐motor neurotransmitter substance K.
British Journal of Pharmacology (1998) 123, 1281–1287; doi:10.1038/sj.bjp.0701734
DOI: 10.1038/sj.bjp.0701734
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